The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently-named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. Airflow into the engine is regulated via a throttle. More specifically, the throttle adjusts throttle area, which increases or decreases airflow into the engine. As the throttle area increases, the airflow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders. As can be appreciated, increasing the air and fuel to the cylinders increases the torque output of the engine.
Engine control systems have been developed to accurately control engine speed output to achieve a desired engine speed. It has been found that the cooling effect of fuel evaporation can lower the charge temperature and increase the volume efficiency (VE). VE quantifies how efficient for the combustion chamber to get the fresh air given intake conditions such as intake pressure and temperature. The manifold absolute pressure (MAP) sensor is unable to indicate the manifold partial pressure for air accurately due to the cooling effect of the fuel evaporation, particularly at high-load conditions. Because the cooling effect happens downstream of the MAP sensor, the MAP sensor does not provide an accurate reading. Therefore, the MAP-based torque may be miscalculated.